Protein's structure key to diving mammals' lengthy breath-holding

June 14, 2013 at 4:00 PM
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LEEDS, England, June 14 (UPI) -- For those wondering how marine animals can hold their breath underwater for so long, British researchers may have an answer: A protein's molecular structure.

A distinctive molecular signature of the oxygen-binding protein myoglobin in diving mammals gave researchers the chance to examine the evolution of the muscle oxygen stores in marine mammals, Science Recorder reported Friday.

Superior mammalian divers have high concentrations of myoglobin -- so high that the muscle color was nearly black instead of red, the University of Leeds said.

Top-notch mammalian divers can hold their breath while under water for more than 60 minutes while searching for food. Land mammals can go without breathing for a few minutes.

Michael Berenbrink, of the University of Liverpool's Institute of Integrative Biology, said researchers examined the electrical charge on the surface of myoglobin and found it became more substantial in mammals considered elite divers, Science Record said. They observed the same molecule signature in whales, seals, beavers and muskrats.

Berenbrink said researchers reconstructed muscle oxygen stores in the ancient ancestors of today's diving mammals by mapping the molecular signature onto the modern-day mammals' family trees.

"Our findings support amphibious ancestries for echidnas, talpid moles, hyraxes, and elephants, thereby not only establishing the earliest land-to-water transition among placental mammals but also providing a new perspective on the evolution of myoglobin, arguably the best-known protein," the researchers said in their paper published in the journal Science.

Since proteins typically stick together in high concentrations, hindering their capacity to do their function, the researchers said they hope their findings will improve understanding of human diseases where protein-gathering is an issue.

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